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Finding the Fourth Proportional to 42.20, 63.31 and 21.92

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Solution

The fourth proportional to 42.20, 63.31 and 21.92 is: 32.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.20 : 63.31 = 21.92 : x
  2. Step 2: Convert to fraction form
    42.20/63.31 = 21.92/x
  3. Step 3: Cross multiply
    42.20x = 63.31 × 21.92
  4. Step 4: Simplify right side
    42.20x = 1,387.33
  5. Step 5: Solve for x
    x = 1,387.33/42.20
  6. Step 6: Final answer
    x = 32.88

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.